route/vendor/github.com/lucas-clemente/quic-go/packet_packer.go

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package quic
import (
"bytes"
"errors"
"fmt"
"github.com/lucas-clemente/quic-go/ackhandler"
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"github.com/lucas-clemente/quic-go/internal/handshake"
"github.com/lucas-clemente/quic-go/internal/protocol"
"github.com/lucas-clemente/quic-go/internal/wire"
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)
type packedPacket struct {
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header *wire.Header
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raw []byte
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frames []wire.Frame
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encryptionLevel protocol.EncryptionLevel
}
type packetPacker struct {
connectionID protocol.ConnectionID
perspective protocol.Perspective
version protocol.VersionNumber
cryptoSetup handshake.CryptoSetup
packetNumberGenerator *packetNumberGenerator
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streamFramer *streamFramer
controlFrames []wire.Frame
stopWaiting *wire.StopWaitingFrame
ackFrame *wire.AckFrame
leastUnacked protocol.PacketNumber
omitConnectionID bool
hasSentPacket bool // has the packetPacker already sent a packet
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}
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func newPacketPacker(connectionID protocol.ConnectionID,
initialPacketNumber protocol.PacketNumber,
cryptoSetup handshake.CryptoSetup,
streamFramer *streamFramer,
perspective protocol.Perspective,
version protocol.VersionNumber,
) *packetPacker {
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return &packetPacker{
cryptoSetup: cryptoSetup,
connectionID: connectionID,
perspective: perspective,
version: version,
streamFramer: streamFramer,
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packetNumberGenerator: newPacketNumberGenerator(initialPacketNumber, protocol.SkipPacketAveragePeriodLength),
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}
}
// PackConnectionClose packs a packet that ONLY contains a ConnectionCloseFrame
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func (p *packetPacker) PackConnectionClose(ccf *wire.ConnectionCloseFrame) (*packedPacket, error) {
frames := []wire.Frame{ccf}
encLevel, sealer := p.cryptoSetup.GetSealer()
header := p.getHeader(encLevel)
raw, err := p.writeAndSealPacket(header, frames, sealer)
return &packedPacket{
header: header,
raw: raw,
frames: frames,
encryptionLevel: encLevel,
}, err
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}
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func (p *packetPacker) PackAckPacket() (*packedPacket, error) {
if p.ackFrame == nil {
return nil, errors.New("packet packer BUG: no ack frame queued")
}
encLevel, sealer := p.cryptoSetup.GetSealer()
header := p.getHeader(encLevel)
frames := []wire.Frame{p.ackFrame}
if p.stopWaiting != nil {
p.stopWaiting.PacketNumber = header.PacketNumber
p.stopWaiting.PacketNumberLen = header.PacketNumberLen
frames = append(frames, p.stopWaiting)
p.stopWaiting = nil
}
p.ackFrame = nil
raw, err := p.writeAndSealPacket(header, frames, sealer)
return &packedPacket{
header: header,
raw: raw,
frames: frames,
encryptionLevel: encLevel,
}, err
}
// PackHandshakeRetransmission retransmits a handshake packet, that was sent with less than forward-secure encryption
func (p *packetPacker) PackHandshakeRetransmission(packet *ackhandler.Packet) (*packedPacket, error) {
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if packet.EncryptionLevel == protocol.EncryptionForwardSecure {
return nil, errors.New("PacketPacker BUG: forward-secure encrypted handshake packets don't need special treatment")
}
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sealer, err := p.cryptoSetup.GetSealerWithEncryptionLevel(packet.EncryptionLevel)
if err != nil {
return nil, err
}
if p.stopWaiting == nil {
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return nil, errors.New("PacketPacker BUG: Handshake retransmissions must contain a StopWaitingFrame")
}
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header := p.getHeader(packet.EncryptionLevel)
p.stopWaiting.PacketNumber = header.PacketNumber
p.stopWaiting.PacketNumberLen = header.PacketNumberLen
frames := append([]wire.Frame{p.stopWaiting}, packet.Frames...)
p.stopWaiting = nil
raw, err := p.writeAndSealPacket(header, frames, sealer)
return &packedPacket{
header: header,
raw: raw,
frames: frames,
encryptionLevel: packet.EncryptionLevel,
}, err
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}
// PackPacket packs a new packet
// the other controlFrames are sent in the next packet, but might be queued and sent in the next packet if the packet would overflow MaxPacketSize otherwise
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func (p *packetPacker) PackPacket() (*packedPacket, error) {
hasCryptoStreamFrame := p.streamFramer.HasCryptoStreamFrame()
// if this is the first packet to be send, make sure it contains stream data
if !p.hasSentPacket && !hasCryptoStreamFrame {
return nil, nil
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}
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if hasCryptoStreamFrame {
return p.packCryptoPacket()
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}
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encLevel, sealer := p.cryptoSetup.GetSealer()
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header := p.getHeader(encLevel)
headerLength, err := header.GetLength(p.perspective, p.version)
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if err != nil {
return nil, err
}
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if p.stopWaiting != nil {
p.stopWaiting.PacketNumber = header.PacketNumber
p.stopWaiting.PacketNumberLen = header.PacketNumberLen
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}
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maxSize := protocol.MaxPacketSize - protocol.ByteCount(sealer.Overhead()) - headerLength
payloadFrames, err := p.composeNextPacket(maxSize, p.canSendData(encLevel))
if err != nil {
return nil, err
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}
// Check if we have enough frames to send
if len(payloadFrames) == 0 {
return nil, nil
}
// Don't send out packets that only contain a StopWaitingFrame
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if len(payloadFrames) == 1 && p.stopWaiting != nil {
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return nil, nil
}
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p.stopWaiting = nil
p.ackFrame = nil
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raw, err := p.writeAndSealPacket(header, payloadFrames, sealer)
if err != nil {
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return nil, err
}
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return &packedPacket{
header: header,
raw: raw,
frames: payloadFrames,
encryptionLevel: encLevel,
}, nil
}
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func (p *packetPacker) packCryptoPacket() (*packedPacket, error) {
encLevel, sealer := p.cryptoSetup.GetSealerForCryptoStream()
header := p.getHeader(encLevel)
headerLength, err := header.GetLength(p.perspective, p.version)
if err != nil {
return nil, err
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}
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maxLen := protocol.MaxPacketSize - protocol.ByteCount(sealer.Overhead()) - protocol.NonForwardSecurePacketSizeReduction - headerLength
frames := []wire.Frame{p.streamFramer.PopCryptoStreamFrame(maxLen)}
raw, err := p.writeAndSealPacket(header, frames, sealer)
if err != nil {
return nil, err
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}
return &packedPacket{
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header: header,
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raw: raw,
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frames: frames,
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encryptionLevel: encLevel,
}, nil
}
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func (p *packetPacker) composeNextPacket(
maxFrameSize protocol.ByteCount,
canSendStreamFrames bool,
) ([]wire.Frame, error) {
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var payloadLength protocol.ByteCount
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var payloadFrames []wire.Frame
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// STOP_WAITING and ACK will always fit
if p.stopWaiting != nil {
payloadFrames = append(payloadFrames, p.stopWaiting)
l, err := p.stopWaiting.MinLength(p.version)
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if err != nil {
return nil, err
}
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payloadLength += l
}
if p.ackFrame != nil {
payloadFrames = append(payloadFrames, p.ackFrame)
l, err := p.ackFrame.MinLength(p.version)
if err != nil {
return nil, err
}
payloadLength += l
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}
for len(p.controlFrames) > 0 {
frame := p.controlFrames[len(p.controlFrames)-1]
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minLength, err := frame.MinLength(p.version)
if err != nil {
return nil, err
}
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if payloadLength+minLength > maxFrameSize {
break
}
payloadFrames = append(payloadFrames, frame)
payloadLength += minLength
p.controlFrames = p.controlFrames[:len(p.controlFrames)-1]
}
if payloadLength > maxFrameSize {
return nil, fmt.Errorf("Packet Packer BUG: packet payload (%d) too large (%d)", payloadLength, maxFrameSize)
}
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if !canSendStreamFrames {
return payloadFrames, nil
}
// temporarily increase the maxFrameSize by the (minimum) length of the DataLen field
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// this leads to a properly sized packet in all cases, since we do all the packet length calculations with StreamFrames that have the DataLen set
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// however, for the last StreamFrame in the packet, we can omit the DataLen, thus yielding a packet of exactly the correct size
// for gQUIC STREAM frames, DataLen is always 2 bytes
// for IETF draft style STREAM frames, the length is encoded to either 1 or 2 bytes
if p.version.UsesIETFFrameFormat() {
maxFrameSize++
} else {
maxFrameSize += 2
}
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fs := p.streamFramer.PopStreamFrames(maxFrameSize - payloadLength)
if len(fs) != 0 {
fs[len(fs)-1].DataLenPresent = false
}
// TODO: Simplify
for _, f := range fs {
payloadFrames = append(payloadFrames, f)
}
for b := p.streamFramer.PopBlockedFrame(); b != nil; b = p.streamFramer.PopBlockedFrame() {
p.controlFrames = append(p.controlFrames, b)
}
return payloadFrames, nil
}
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func (p *packetPacker) QueueControlFrame(frame wire.Frame) {
switch f := frame.(type) {
case *wire.StopWaitingFrame:
p.stopWaiting = f
case *wire.AckFrame:
p.ackFrame = f
default:
p.controlFrames = append(p.controlFrames, f)
}
}
func (p *packetPacker) getHeader(encLevel protocol.EncryptionLevel) *wire.Header {
pnum := p.packetNumberGenerator.Peek()
packetNumberLen := protocol.GetPacketNumberLengthForHeader(pnum, p.leastUnacked)
header := &wire.Header{
ConnectionID: p.connectionID,
PacketNumber: pnum,
PacketNumberLen: packetNumberLen,
}
if p.version.UsesTLS() && encLevel != protocol.EncryptionForwardSecure {
header.PacketNumberLen = protocol.PacketNumberLen4
header.IsLongHeader = true
if !p.hasSentPacket && p.perspective == protocol.PerspectiveClient {
header.Type = protocol.PacketTypeInitial
} else {
header.Type = protocol.PacketTypeHandshake
}
}
if p.omitConnectionID && encLevel == protocol.EncryptionForwardSecure {
header.OmitConnectionID = true
}
if !p.version.UsesTLS() {
if p.perspective == protocol.PerspectiveServer && encLevel == protocol.EncryptionSecure {
header.DiversificationNonce = p.cryptoSetup.DiversificationNonce()
}
if p.perspective == protocol.PerspectiveClient && encLevel != protocol.EncryptionForwardSecure {
header.VersionFlag = true
header.Version = p.version
}
} else {
if encLevel != protocol.EncryptionForwardSecure {
header.Version = p.version
}
}
return header
}
func (p *packetPacker) writeAndSealPacket(
header *wire.Header,
payloadFrames []wire.Frame,
sealer handshake.Sealer,
) ([]byte, error) {
raw := getPacketBuffer()
buffer := bytes.NewBuffer(raw)
if err := header.Write(buffer, p.perspective, p.version); err != nil {
return nil, err
}
payloadStartIndex := buffer.Len()
// the Initial packet needs to be padded, so the last STREAM frame must have the data length present
if header.Type == protocol.PacketTypeInitial {
lastFrame := payloadFrames[len(payloadFrames)-1]
if sf, ok := lastFrame.(*wire.StreamFrame); ok {
sf.DataLenPresent = true
}
}
for _, frame := range payloadFrames {
if err := frame.Write(buffer, p.version); err != nil {
return nil, err
}
}
// if this is an IETF QUIC Initial packet, we need to pad it to fulfill the minimum size requirement
// in gQUIC, padding is handled in the CHLO
if header.Type == protocol.PacketTypeInitial {
paddingLen := protocol.MinInitialPacketSize - sealer.Overhead() - buffer.Len()
if paddingLen > 0 {
buffer.Write(bytes.Repeat([]byte{0}, paddingLen))
}
}
if protocol.ByteCount(buffer.Len()+sealer.Overhead()) > protocol.MaxPacketSize {
return nil, errors.New("PacketPacker BUG: packet too large")
}
raw = raw[0:buffer.Len()]
_ = sealer.Seal(raw[payloadStartIndex:payloadStartIndex], raw[payloadStartIndex:], header.PacketNumber, raw[:payloadStartIndex])
raw = raw[0 : buffer.Len()+sealer.Overhead()]
num := p.packetNumberGenerator.Pop()
if num != header.PacketNumber {
return nil, errors.New("packetPacker BUG: Peeked and Popped packet numbers do not match")
}
p.hasSentPacket = true
return raw, nil
}
func (p *packetPacker) canSendData(encLevel protocol.EncryptionLevel) bool {
if p.perspective == protocol.PerspectiveClient {
return encLevel >= protocol.EncryptionSecure
}
return encLevel == protocol.EncryptionForwardSecure
}
func (p *packetPacker) SetLeastUnacked(leastUnacked protocol.PacketNumber) {
p.leastUnacked = leastUnacked
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}
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func (p *packetPacker) SetOmitConnectionID() {
p.omitConnectionID = true
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}